The present article reports on a simple, economical, and green preparative strategy toward water-soluble, fluorescent carbon nanoparticles (CPs) with a quantum yield of approximately 6.9% by hydrothermal process using low cost wastes of pomelo peel as a carbon source for the first time. We further explore the use of such CPs as probes for a fluorescent Hg(2+) detection application, which is based on Hg(2+)-induced fluorescence quenching of CPs. This sensing system exhibits excellent sensitivity and selectivity toward Hg(2+), and a detection limit as low as 0.23 nM is achieved. The practical use of this system for Hg(2+) determination in lake water samples is also demonstrated successfully.

In this contribution, we demonstrate a green, cost-effective, one-pot preparative route toward Ag nanoparticles-graphene (AgNPs-G) nanocomposites in aqueous solution with the use of tannic acid (TA), an environmentally friendly and water-soluble polyphenol, as a reducing agent. Such AgNPs-G nanocomposites were synthesized through one-pot reduction of AgNO 3 and GO by TA. We investigated surface enhanced Raman scattering (SERS) and electrochemical properties of the resultant AgNPs-G nanocomposites. It is found that such AgNPs-G nanocomposites show excellent SERS activity as SERS substrates and exhibit notable catalytic performance toward the reduction of H 2 O 2 . This enzymeless H 2 O 2 sensor has a fast amperometric response time of less than 2 s. The linear range is estimated to be from 1 6 10 24 M to 0.01 M (r = 0.999) and the detection limit is estimated to be 7 6 10 26 M at a signal-to-noise ratio of 3. A glucose biosensor was further fabricated by immobilizing glucose oxidase (GOD) into chitosan-AgNPs-G nanocomposite film on the surface of a glassy carbon electrode (GCE). This sensor exhibits good response to glucose, and the linear response range is estimated to be from 2 to 10 mM (R = 0.996) at 20.5 V. The detection limit of 100 mM was achieved at a signal-to-noise ratio of 3. More importantly, we demonstrate successfully its application for glucose detection in human blood serum.

Recently, a new coronavirus was isolated from the lung tissue of autopsy sample and nasal/throat swabs of the patients with Severe Acute Respiratory Syndrome (SARS) and the causative association with SARS was determined. To reveal further the characteristics of the virus and to provide insight about the molecular mechanism of SARS etiology, a proteomic strategy was utilized to identify the structural proteins of SARS coronavirus (SARS-CoV) isolated from Vero E6 cells infected with the BJ-01 strain of the virus. At first, Western blotting with the convalescent sera from SARS patients demonstrated that there were various structural proteins of SARS-CoV in the cultured supernatant of virus infected-Vero E6 cells and that nucleocaspid (N) protein had a prominent immunogenicity to the convalescent sera from the patients with SARS, while the immune response of spike (S) protein probably binding with membrane (M) glycoprotein was much weaker. Then, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to separate the complex protein constituents, and the strategy of continuous slicing from loading well to the bottom of the gels was utilized to search thoroughly the structural proteins of the virus. The proteins in sliced slots were trypsinized in-gel and identified by mass spectrometry. Three structural proteins named S, N and M proteins of SARS-CoV were uncovered with the sequence coverage of 38.9, 93.1 and 28.1% respectively. Glycosylation modification in S protein was also analyzed and four glycosylation sites were discovered by comparing the mass spectra before and after deglycosylation of the peptides with PNGase F digestion. Matrix-assisted laser desorption/ionization-mass spectrometry determination showed that relative molecular weight of intact N protein is 45 929 Da, which is very close to its theoretically calculated molecular weight 45 935 Da based on the amino acid sequence deduced from the genome with the first amino acid methionine at the N-terminus depleted and second, serine, acetylated, indicating that phosphorylation does not happen at all in the predicted phosphorylation sites within infected cells nor in virus particles. Intriguingly, a series of shorter isoforms of N protein was observed by SDS-PAGE and identified by mass spectrometry characterization. For further confirmation of this phenomenon and its related mechanism, recombinant N protein of SARS-CoV was cleaved in vitro by caspase-3 and -6 respectively. The results demonstrated that these shorter isoforms could be the products from cleavage of caspase-3 rather than that of caspase-6. Further, the relationship between the caspase cleavage and the viral infection to the host cell is discussed.